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1 | /* |
2 | * Functions related to setting various queue properties from drivers |
3 | */ |
4 | #include <linux/kernel.h> |
5 | #include <linux/module.h> |
6 | #include <linux/init.h> |
7 | #include <linux/bio.h> |
8 | #include <linux/blkdev.h> |
9 | #include <linux/bootmem.h> /* for max_pfn/max_low_pfn */ |
10 | #include <linux/gcd.h> |
11 | #include <linux/lcm.h> |
12 | #include <linux/jiffies.h> |
13 | #include <linux/gfp.h> |
14 | |
15 | #include "blk.h" |
16 | |
17 | unsigned long blk_max_low_pfn; |
18 | EXPORT_SYMBOL(blk_max_low_pfn); |
19 | |
20 | unsigned long blk_max_pfn; |
21 | |
22 | /** |
23 | * blk_queue_prep_rq - set a prepare_request function for queue |
24 | * @q: queue |
25 | * @pfn: prepare_request function |
26 | * |
27 | * It's possible for a queue to register a prepare_request callback which |
28 | * is invoked before the request is handed to the request_fn. The goal of |
29 | * the function is to prepare a request for I/O, it can be used to build a |
30 | * cdb from the request data for instance. |
31 | * |
32 | */ |
33 | void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn) |
34 | { |
35 | q->prep_rq_fn = pfn; |
36 | } |
37 | EXPORT_SYMBOL(blk_queue_prep_rq); |
38 | |
39 | /** |
40 | * blk_queue_unprep_rq - set an unprepare_request function for queue |
41 | * @q: queue |
42 | * @ufn: unprepare_request function |
43 | * |
44 | * It's possible for a queue to register an unprepare_request callback |
45 | * which is invoked before the request is finally completed. The goal |
46 | * of the function is to deallocate any data that was allocated in the |
47 | * prepare_request callback. |
48 | * |
49 | */ |
50 | void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn) |
51 | { |
52 | q->unprep_rq_fn = ufn; |
53 | } |
54 | EXPORT_SYMBOL(blk_queue_unprep_rq); |
55 | |
56 | /** |
57 | * blk_queue_merge_bvec - set a merge_bvec function for queue |
58 | * @q: queue |
59 | * @mbfn: merge_bvec_fn |
60 | * |
61 | * Usually queues have static limitations on the max sectors or segments that |
62 | * we can put in a request. Stacking drivers may have some settings that |
63 | * are dynamic, and thus we have to query the queue whether it is ok to |
64 | * add a new bio_vec to a bio at a given offset or not. If the block device |
65 | * has such limitations, it needs to register a merge_bvec_fn to control |
66 | * the size of bio's sent to it. Note that a block device *must* allow a |
67 | * single page to be added to an empty bio. The block device driver may want |
68 | * to use the bio_split() function to deal with these bio's. By default |
69 | * no merge_bvec_fn is defined for a queue, and only the fixed limits are |
70 | * honored. |
71 | */ |
72 | void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn) |
73 | { |
74 | q->merge_bvec_fn = mbfn; |
75 | } |
76 | EXPORT_SYMBOL(blk_queue_merge_bvec); |
77 | |
78 | void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn) |
79 | { |
80 | q->softirq_done_fn = fn; |
81 | } |
82 | EXPORT_SYMBOL(blk_queue_softirq_done); |
83 | |
84 | void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout) |
85 | { |
86 | q->rq_timeout = timeout; |
87 | } |
88 | EXPORT_SYMBOL_GPL(blk_queue_rq_timeout); |
89 | |
90 | void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn) |
91 | { |
92 | q->rq_timed_out_fn = fn; |
93 | } |
94 | EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out); |
95 | |
96 | void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn) |
97 | { |
98 | q->lld_busy_fn = fn; |
99 | } |
100 | EXPORT_SYMBOL_GPL(blk_queue_lld_busy); |
101 | |
102 | /** |
103 | * blk_set_default_limits - reset limits to default values |
104 | * @lim: the queue_limits structure to reset |
105 | * |
106 | * Description: |
107 | * Returns a queue_limit struct to its default state. Can be used by |
108 | * stacking drivers like DM that stage table swaps and reuse an |
109 | * existing device queue. |
110 | */ |
111 | void blk_set_default_limits(struct queue_limits *lim) |
112 | { |
113 | lim->max_segments = BLK_MAX_SEGMENTS; |
114 | lim->max_integrity_segments = 0; |
115 | lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; |
116 | lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; |
117 | lim->max_sectors = BLK_DEF_MAX_SECTORS; |
118 | lim->max_hw_sectors = INT_MAX; |
119 | lim->max_discard_sectors = 0; |
120 | lim->discard_granularity = 0; |
121 | lim->discard_alignment = 0; |
122 | lim->discard_misaligned = 0; |
123 | lim->discard_zeroes_data = 1; |
124 | lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; |
125 | lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); |
126 | lim->alignment_offset = 0; |
127 | lim->io_opt = 0; |
128 | lim->misaligned = 0; |
129 | lim->cluster = 1; |
130 | } |
131 | EXPORT_SYMBOL(blk_set_default_limits); |
132 | |
133 | /** |
134 | * blk_queue_make_request - define an alternate make_request function for a device |
135 | * @q: the request queue for the device to be affected |
136 | * @mfn: the alternate make_request function |
137 | * |
138 | * Description: |
139 | * The normal way for &struct bios to be passed to a device |
140 | * driver is for them to be collected into requests on a request |
141 | * queue, and then to allow the device driver to select requests |
142 | * off that queue when it is ready. This works well for many block |
143 | * devices. However some block devices (typically virtual devices |
144 | * such as md or lvm) do not benefit from the processing on the |
145 | * request queue, and are served best by having the requests passed |
146 | * directly to them. This can be achieved by providing a function |
147 | * to blk_queue_make_request(). |
148 | * |
149 | * Caveat: |
150 | * The driver that does this *must* be able to deal appropriately |
151 | * with buffers in "highmemory". This can be accomplished by either calling |
152 | * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling |
153 | * blk_queue_bounce() to create a buffer in normal memory. |
154 | **/ |
155 | void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) |
156 | { |
157 | /* |
158 | * set defaults |
159 | */ |
160 | q->nr_requests = BLKDEV_MAX_RQ; |
161 | |
162 | q->make_request_fn = mfn; |
163 | blk_queue_dma_alignment(q, 511); |
164 | blk_queue_congestion_threshold(q); |
165 | q->nr_batching = BLK_BATCH_REQ; |
166 | |
167 | blk_set_default_limits(&q->limits); |
168 | blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS); |
169 | q->limits.discard_zeroes_data = 0; |
170 | |
171 | /* |
172 | * by default assume old behaviour and bounce for any highmem page |
173 | */ |
174 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); |
175 | } |
176 | EXPORT_SYMBOL(blk_queue_make_request); |
177 | |
178 | /** |
179 | * blk_queue_bounce_limit - set bounce buffer limit for queue |
180 | * @q: the request queue for the device |
181 | * @dma_mask: the maximum address the device can handle |
182 | * |
183 | * Description: |
184 | * Different hardware can have different requirements as to what pages |
185 | * it can do I/O directly to. A low level driver can call |
186 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce |
187 | * buffers for doing I/O to pages residing above @dma_mask. |
188 | **/ |
189 | void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask) |
190 | { |
191 | unsigned long b_pfn = dma_mask >> PAGE_SHIFT; |
192 | int dma = 0; |
193 | |
194 | q->bounce_gfp = GFP_NOIO; |
195 | #if BITS_PER_LONG == 64 |
196 | /* |
197 | * Assume anything <= 4GB can be handled by IOMMU. Actually |
198 | * some IOMMUs can handle everything, but I don't know of a |
199 | * way to test this here. |
200 | */ |
201 | if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) |
202 | dma = 1; |
203 | q->limits.bounce_pfn = max(max_low_pfn, b_pfn); |
204 | #else |
205 | if (b_pfn < blk_max_low_pfn) |
206 | dma = 1; |
207 | q->limits.bounce_pfn = b_pfn; |
208 | #endif |
209 | if (dma) { |
210 | init_emergency_isa_pool(); |
211 | q->bounce_gfp = GFP_NOIO | GFP_DMA; |
212 | q->limits.bounce_pfn = b_pfn; |
213 | } |
214 | } |
215 | EXPORT_SYMBOL(blk_queue_bounce_limit); |
216 | |
217 | /** |
218 | * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request |
219 | * @limits: the queue limits |
220 | * @max_hw_sectors: max hardware sectors in the usual 512b unit |
221 | * |
222 | * Description: |
223 | * Enables a low level driver to set a hard upper limit, |
224 | * max_hw_sectors, on the size of requests. max_hw_sectors is set by |
225 | * the device driver based upon the combined capabilities of I/O |
226 | * controller and storage device. |
227 | * |
228 | * max_sectors is a soft limit imposed by the block layer for |
229 | * filesystem type requests. This value can be overridden on a |
230 | * per-device basis in /sys/block/<device>/queue/max_sectors_kb. |
231 | * The soft limit can not exceed max_hw_sectors. |
232 | **/ |
233 | void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors) |
234 | { |
235 | if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) { |
236 | max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9); |
237 | printk(KERN_INFO "%s: set to minimum %d\n", |
238 | __func__, max_hw_sectors); |
239 | } |
240 | |
241 | limits->max_hw_sectors = max_hw_sectors; |
242 | limits->max_sectors = min_t(unsigned int, max_hw_sectors, |
243 | BLK_DEF_MAX_SECTORS); |
244 | } |
245 | EXPORT_SYMBOL(blk_limits_max_hw_sectors); |
246 | |
247 | /** |
248 | * blk_queue_max_hw_sectors - set max sectors for a request for this queue |
249 | * @q: the request queue for the device |
250 | * @max_hw_sectors: max hardware sectors in the usual 512b unit |
251 | * |
252 | * Description: |
253 | * See description for blk_limits_max_hw_sectors(). |
254 | **/ |
255 | void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) |
256 | { |
257 | blk_limits_max_hw_sectors(&q->limits, max_hw_sectors); |
258 | } |
259 | EXPORT_SYMBOL(blk_queue_max_hw_sectors); |
260 | |
261 | /** |
262 | * blk_queue_max_discard_sectors - set max sectors for a single discard |
263 | * @q: the request queue for the device |
264 | * @max_discard_sectors: maximum number of sectors to discard |
265 | **/ |
266 | void blk_queue_max_discard_sectors(struct request_queue *q, |
267 | unsigned int max_discard_sectors) |
268 | { |
269 | q->limits.max_discard_sectors = max_discard_sectors; |
270 | } |
271 | EXPORT_SYMBOL(blk_queue_max_discard_sectors); |
272 | |
273 | /** |
274 | * blk_queue_max_segments - set max hw segments for a request for this queue |
275 | * @q: the request queue for the device |
276 | * @max_segments: max number of segments |
277 | * |
278 | * Description: |
279 | * Enables a low level driver to set an upper limit on the number of |
280 | * hw data segments in a request. |
281 | **/ |
282 | void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments) |
283 | { |
284 | if (!max_segments) { |
285 | max_segments = 1; |
286 | printk(KERN_INFO "%s: set to minimum %d\n", |
287 | __func__, max_segments); |
288 | } |
289 | |
290 | q->limits.max_segments = max_segments; |
291 | } |
292 | EXPORT_SYMBOL(blk_queue_max_segments); |
293 | |
294 | /** |
295 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg |
296 | * @q: the request queue for the device |
297 | * @max_size: max size of segment in bytes |
298 | * |
299 | * Description: |
300 | * Enables a low level driver to set an upper limit on the size of a |
301 | * coalesced segment |
302 | **/ |
303 | void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) |
304 | { |
305 | if (max_size < PAGE_CACHE_SIZE) { |
306 | max_size = PAGE_CACHE_SIZE; |
307 | printk(KERN_INFO "%s: set to minimum %d\n", |
308 | __func__, max_size); |
309 | } |
310 | |
311 | q->limits.max_segment_size = max_size; |
312 | } |
313 | EXPORT_SYMBOL(blk_queue_max_segment_size); |
314 | |
315 | /** |
316 | * blk_queue_logical_block_size - set logical block size for the queue |
317 | * @q: the request queue for the device |
318 | * @size: the logical block size, in bytes |
319 | * |
320 | * Description: |
321 | * This should be set to the lowest possible block size that the |
322 | * storage device can address. The default of 512 covers most |
323 | * hardware. |
324 | **/ |
325 | void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) |
326 | { |
327 | q->limits.logical_block_size = size; |
328 | |
329 | if (q->limits.physical_block_size < size) |
330 | q->limits.physical_block_size = size; |
331 | |
332 | if (q->limits.io_min < q->limits.physical_block_size) |
333 | q->limits.io_min = q->limits.physical_block_size; |
334 | } |
335 | EXPORT_SYMBOL(blk_queue_logical_block_size); |
336 | |
337 | /** |
338 | * blk_queue_physical_block_size - set physical block size for the queue |
339 | * @q: the request queue for the device |
340 | * @size: the physical block size, in bytes |
341 | * |
342 | * Description: |
343 | * This should be set to the lowest possible sector size that the |
344 | * hardware can operate on without reverting to read-modify-write |
345 | * operations. |
346 | */ |
347 | void blk_queue_physical_block_size(struct request_queue *q, unsigned int size) |
348 | { |
349 | q->limits.physical_block_size = size; |
350 | |
351 | if (q->limits.physical_block_size < q->limits.logical_block_size) |
352 | q->limits.physical_block_size = q->limits.logical_block_size; |
353 | |
354 | if (q->limits.io_min < q->limits.physical_block_size) |
355 | q->limits.io_min = q->limits.physical_block_size; |
356 | } |
357 | EXPORT_SYMBOL(blk_queue_physical_block_size); |
358 | |
359 | /** |
360 | * blk_queue_alignment_offset - set physical block alignment offset |
361 | * @q: the request queue for the device |
362 | * @offset: alignment offset in bytes |
363 | * |
364 | * Description: |
365 | * Some devices are naturally misaligned to compensate for things like |
366 | * the legacy DOS partition table 63-sector offset. Low-level drivers |
367 | * should call this function for devices whose first sector is not |
368 | * naturally aligned. |
369 | */ |
370 | void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) |
371 | { |
372 | q->limits.alignment_offset = |
373 | offset & (q->limits.physical_block_size - 1); |
374 | q->limits.misaligned = 0; |
375 | } |
376 | EXPORT_SYMBOL(blk_queue_alignment_offset); |
377 | |
378 | /** |
379 | * blk_limits_io_min - set minimum request size for a device |
380 | * @limits: the queue limits |
381 | * @min: smallest I/O size in bytes |
382 | * |
383 | * Description: |
384 | * Some devices have an internal block size bigger than the reported |
385 | * hardware sector size. This function can be used to signal the |
386 | * smallest I/O the device can perform without incurring a performance |
387 | * penalty. |
388 | */ |
389 | void blk_limits_io_min(struct queue_limits *limits, unsigned int min) |
390 | { |
391 | limits->io_min = min; |
392 | |
393 | if (limits->io_min < limits->logical_block_size) |
394 | limits->io_min = limits->logical_block_size; |
395 | |
396 | if (limits->io_min < limits->physical_block_size) |
397 | limits->io_min = limits->physical_block_size; |
398 | } |
399 | EXPORT_SYMBOL(blk_limits_io_min); |
400 | |
401 | /** |
402 | * blk_queue_io_min - set minimum request size for the queue |
403 | * @q: the request queue for the device |
404 | * @min: smallest I/O size in bytes |
405 | * |
406 | * Description: |
407 | * Storage devices may report a granularity or preferred minimum I/O |
408 | * size which is the smallest request the device can perform without |
409 | * incurring a performance penalty. For disk drives this is often the |
410 | * physical block size. For RAID arrays it is often the stripe chunk |
411 | * size. A properly aligned multiple of minimum_io_size is the |
412 | * preferred request size for workloads where a high number of I/O |
413 | * operations is desired. |
414 | */ |
415 | void blk_queue_io_min(struct request_queue *q, unsigned int min) |
416 | { |
417 | blk_limits_io_min(&q->limits, min); |
418 | } |
419 | EXPORT_SYMBOL(blk_queue_io_min); |
420 | |
421 | /** |
422 | * blk_limits_io_opt - set optimal request size for a device |
423 | * @limits: the queue limits |
424 | * @opt: smallest I/O size in bytes |
425 | * |
426 | * Description: |
427 | * Storage devices may report an optimal I/O size, which is the |
428 | * device's preferred unit for sustained I/O. This is rarely reported |
429 | * for disk drives. For RAID arrays it is usually the stripe width or |
430 | * the internal track size. A properly aligned multiple of |
431 | * optimal_io_size is the preferred request size for workloads where |
432 | * sustained throughput is desired. |
433 | */ |
434 | void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) |
435 | { |
436 | limits->io_opt = opt; |
437 | } |
438 | EXPORT_SYMBOL(blk_limits_io_opt); |
439 | |
440 | /** |
441 | * blk_queue_io_opt - set optimal request size for the queue |
442 | * @q: the request queue for the device |
443 | * @opt: optimal request size in bytes |
444 | * |
445 | * Description: |
446 | * Storage devices may report an optimal I/O size, which is the |
447 | * device's preferred unit for sustained I/O. This is rarely reported |
448 | * for disk drives. For RAID arrays it is usually the stripe width or |
449 | * the internal track size. A properly aligned multiple of |
450 | * optimal_io_size is the preferred request size for workloads where |
451 | * sustained throughput is desired. |
452 | */ |
453 | void blk_queue_io_opt(struct request_queue *q, unsigned int opt) |
454 | { |
455 | blk_limits_io_opt(&q->limits, opt); |
456 | } |
457 | EXPORT_SYMBOL(blk_queue_io_opt); |
458 | |
459 | /** |
460 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers |
461 | * @t: the stacking driver (top) |
462 | * @b: the underlying device (bottom) |
463 | **/ |
464 | void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) |
465 | { |
466 | blk_stack_limits(&t->limits, &b->limits, 0); |
467 | } |
468 | EXPORT_SYMBOL(blk_queue_stack_limits); |
469 | |
470 | /** |
471 | * blk_stack_limits - adjust queue_limits for stacked devices |
472 | * @t: the stacking driver limits (top device) |
473 | * @b: the underlying queue limits (bottom, component device) |
474 | * @start: first data sector within component device |
475 | * |
476 | * Description: |
477 | * This function is used by stacking drivers like MD and DM to ensure |
478 | * that all component devices have compatible block sizes and |
479 | * alignments. The stacking driver must provide a queue_limits |
480 | * struct (top) and then iteratively call the stacking function for |
481 | * all component (bottom) devices. The stacking function will |
482 | * attempt to combine the values and ensure proper alignment. |
483 | * |
484 | * Returns 0 if the top and bottom queue_limits are compatible. The |
485 | * top device's block sizes and alignment offsets may be adjusted to |
486 | * ensure alignment with the bottom device. If no compatible sizes |
487 | * and alignments exist, -1 is returned and the resulting top |
488 | * queue_limits will have the misaligned flag set to indicate that |
489 | * the alignment_offset is undefined. |
490 | */ |
491 | int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, |
492 | sector_t start) |
493 | { |
494 | unsigned int top, bottom, alignment, ret = 0; |
495 | |
496 | t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); |
497 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); |
498 | t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); |
499 | |
500 | t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, |
501 | b->seg_boundary_mask); |
502 | |
503 | t->max_segments = min_not_zero(t->max_segments, b->max_segments); |
504 | t->max_integrity_segments = min_not_zero(t->max_integrity_segments, |
505 | b->max_integrity_segments); |
506 | |
507 | t->max_segment_size = min_not_zero(t->max_segment_size, |
508 | b->max_segment_size); |
509 | |
510 | t->misaligned |= b->misaligned; |
511 | |
512 | alignment = queue_limit_alignment_offset(b, start); |
513 | |
514 | /* Bottom device has different alignment. Check that it is |
515 | * compatible with the current top alignment. |
516 | */ |
517 | if (t->alignment_offset != alignment) { |
518 | |
519 | top = max(t->physical_block_size, t->io_min) |
520 | + t->alignment_offset; |
521 | bottom = max(b->physical_block_size, b->io_min) + alignment; |
522 | |
523 | /* Verify that top and bottom intervals line up */ |
524 | if (max(top, bottom) & (min(top, bottom) - 1)) { |
525 | t->misaligned = 1; |
526 | ret = -1; |
527 | } |
528 | } |
529 | |
530 | t->logical_block_size = max(t->logical_block_size, |
531 | b->logical_block_size); |
532 | |
533 | t->physical_block_size = max(t->physical_block_size, |
534 | b->physical_block_size); |
535 | |
536 | t->io_min = max(t->io_min, b->io_min); |
537 | t->io_opt = lcm(t->io_opt, b->io_opt); |
538 | |
539 | t->cluster &= b->cluster; |
540 | t->discard_zeroes_data &= b->discard_zeroes_data; |
541 | |
542 | /* Physical block size a multiple of the logical block size? */ |
543 | if (t->physical_block_size & (t->logical_block_size - 1)) { |
544 | t->physical_block_size = t->logical_block_size; |
545 | t->misaligned = 1; |
546 | ret = -1; |
547 | } |
548 | |
549 | /* Minimum I/O a multiple of the physical block size? */ |
550 | if (t->io_min & (t->physical_block_size - 1)) { |
551 | t->io_min = t->physical_block_size; |
552 | t->misaligned = 1; |
553 | ret = -1; |
554 | } |
555 | |
556 | /* Optimal I/O a multiple of the physical block size? */ |
557 | if (t->io_opt & (t->physical_block_size - 1)) { |
558 | t->io_opt = 0; |
559 | t->misaligned = 1; |
560 | ret = -1; |
561 | } |
562 | |
563 | /* Find lowest common alignment_offset */ |
564 | t->alignment_offset = lcm(t->alignment_offset, alignment) |
565 | & (max(t->physical_block_size, t->io_min) - 1); |
566 | |
567 | /* Verify that new alignment_offset is on a logical block boundary */ |
568 | if (t->alignment_offset & (t->logical_block_size - 1)) { |
569 | t->misaligned = 1; |
570 | ret = -1; |
571 | } |
572 | |
573 | /* Discard alignment and granularity */ |
574 | if (b->discard_granularity) { |
575 | alignment = queue_limit_discard_alignment(b, start); |
576 | |
577 | if (t->discard_granularity != 0 && |
578 | t->discard_alignment != alignment) { |
579 | top = t->discard_granularity + t->discard_alignment; |
580 | bottom = b->discard_granularity + alignment; |
581 | |
582 | /* Verify that top and bottom intervals line up */ |
583 | if (max(top, bottom) & (min(top, bottom) - 1)) |
584 | t->discard_misaligned = 1; |
585 | } |
586 | |
587 | t->max_discard_sectors = min_not_zero(t->max_discard_sectors, |
588 | b->max_discard_sectors); |
589 | t->discard_granularity = max(t->discard_granularity, |
590 | b->discard_granularity); |
591 | t->discard_alignment = lcm(t->discard_alignment, alignment) & |
592 | (t->discard_granularity - 1); |
593 | } |
594 | |
595 | return ret; |
596 | } |
597 | EXPORT_SYMBOL(blk_stack_limits); |
598 | |
599 | /** |
600 | * bdev_stack_limits - adjust queue limits for stacked drivers |
601 | * @t: the stacking driver limits (top device) |
602 | * @bdev: the component block_device (bottom) |
603 | * @start: first data sector within component device |
604 | * |
605 | * Description: |
606 | * Merges queue limits for a top device and a block_device. Returns |
607 | * 0 if alignment didn't change. Returns -1 if adding the bottom |
608 | * device caused misalignment. |
609 | */ |
610 | int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev, |
611 | sector_t start) |
612 | { |
613 | struct request_queue *bq = bdev_get_queue(bdev); |
614 | |
615 | start += get_start_sect(bdev); |
616 | |
617 | return blk_stack_limits(t, &bq->limits, start); |
618 | } |
619 | EXPORT_SYMBOL(bdev_stack_limits); |
620 | |
621 | /** |
622 | * disk_stack_limits - adjust queue limits for stacked drivers |
623 | * @disk: MD/DM gendisk (top) |
624 | * @bdev: the underlying block device (bottom) |
625 | * @offset: offset to beginning of data within component device |
626 | * |
627 | * Description: |
628 | * Merges the limits for a top level gendisk and a bottom level |
629 | * block_device. |
630 | */ |
631 | void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, |
632 | sector_t offset) |
633 | { |
634 | struct request_queue *t = disk->queue; |
635 | |
636 | if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) { |
637 | char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; |
638 | |
639 | disk_name(disk, 0, top); |
640 | bdevname(bdev, bottom); |
641 | |
642 | printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", |
643 | top, bottom); |
644 | } |
645 | } |
646 | EXPORT_SYMBOL(disk_stack_limits); |
647 | |
648 | /** |
649 | * blk_queue_dma_pad - set pad mask |
650 | * @q: the request queue for the device |
651 | * @mask: pad mask |
652 | * |
653 | * Set dma pad mask. |
654 | * |
655 | * Appending pad buffer to a request modifies the last entry of a |
656 | * scatter list such that it includes the pad buffer. |
657 | **/ |
658 | void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) |
659 | { |
660 | q->dma_pad_mask = mask; |
661 | } |
662 | EXPORT_SYMBOL(blk_queue_dma_pad); |
663 | |
664 | /** |
665 | * blk_queue_update_dma_pad - update pad mask |
666 | * @q: the request queue for the device |
667 | * @mask: pad mask |
668 | * |
669 | * Update dma pad mask. |
670 | * |
671 | * Appending pad buffer to a request modifies the last entry of a |
672 | * scatter list such that it includes the pad buffer. |
673 | **/ |
674 | void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) |
675 | { |
676 | if (mask > q->dma_pad_mask) |
677 | q->dma_pad_mask = mask; |
678 | } |
679 | EXPORT_SYMBOL(blk_queue_update_dma_pad); |
680 | |
681 | /** |
682 | * blk_queue_dma_drain - Set up a drain buffer for excess dma. |
683 | * @q: the request queue for the device |
684 | * @dma_drain_needed: fn which returns non-zero if drain is necessary |
685 | * @buf: physically contiguous buffer |
686 | * @size: size of the buffer in bytes |
687 | * |
688 | * Some devices have excess DMA problems and can't simply discard (or |
689 | * zero fill) the unwanted piece of the transfer. They have to have a |
690 | * real area of memory to transfer it into. The use case for this is |
691 | * ATAPI devices in DMA mode. If the packet command causes a transfer |
692 | * bigger than the transfer size some HBAs will lock up if there |
693 | * aren't DMA elements to contain the excess transfer. What this API |
694 | * does is adjust the queue so that the buf is always appended |
695 | * silently to the scatterlist. |
696 | * |
697 | * Note: This routine adjusts max_hw_segments to make room for appending |
698 | * the drain buffer. If you call blk_queue_max_segments() after calling |
699 | * this routine, you must set the limit to one fewer than your device |
700 | * can support otherwise there won't be room for the drain buffer. |
701 | */ |
702 | int blk_queue_dma_drain(struct request_queue *q, |
703 | dma_drain_needed_fn *dma_drain_needed, |
704 | void *buf, unsigned int size) |
705 | { |
706 | if (queue_max_segments(q) < 2) |
707 | return -EINVAL; |
708 | /* make room for appending the drain */ |
709 | blk_queue_max_segments(q, queue_max_segments(q) - 1); |
710 | q->dma_drain_needed = dma_drain_needed; |
711 | q->dma_drain_buffer = buf; |
712 | q->dma_drain_size = size; |
713 | |
714 | return 0; |
715 | } |
716 | EXPORT_SYMBOL_GPL(blk_queue_dma_drain); |
717 | |
718 | /** |
719 | * blk_queue_segment_boundary - set boundary rules for segment merging |
720 | * @q: the request queue for the device |
721 | * @mask: the memory boundary mask |
722 | **/ |
723 | void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) |
724 | { |
725 | if (mask < PAGE_CACHE_SIZE - 1) { |
726 | mask = PAGE_CACHE_SIZE - 1; |
727 | printk(KERN_INFO "%s: set to minimum %lx\n", |
728 | __func__, mask); |
729 | } |
730 | |
731 | q->limits.seg_boundary_mask = mask; |
732 | } |
733 | EXPORT_SYMBOL(blk_queue_segment_boundary); |
734 | |
735 | /** |
736 | * blk_queue_dma_alignment - set dma length and memory alignment |
737 | * @q: the request queue for the device |
738 | * @mask: alignment mask |
739 | * |
740 | * description: |
741 | * set required memory and length alignment for direct dma transactions. |
742 | * this is used when building direct io requests for the queue. |
743 | * |
744 | **/ |
745 | void blk_queue_dma_alignment(struct request_queue *q, int mask) |
746 | { |
747 | q->dma_alignment = mask; |
748 | } |
749 | EXPORT_SYMBOL(blk_queue_dma_alignment); |
750 | |
751 | /** |
752 | * blk_queue_update_dma_alignment - update dma length and memory alignment |
753 | * @q: the request queue for the device |
754 | * @mask: alignment mask |
755 | * |
756 | * description: |
757 | * update required memory and length alignment for direct dma transactions. |
758 | * If the requested alignment is larger than the current alignment, then |
759 | * the current queue alignment is updated to the new value, otherwise it |
760 | * is left alone. The design of this is to allow multiple objects |
761 | * (driver, device, transport etc) to set their respective |
762 | * alignments without having them interfere. |
763 | * |
764 | **/ |
765 | void blk_queue_update_dma_alignment(struct request_queue *q, int mask) |
766 | { |
767 | BUG_ON(mask > PAGE_SIZE); |
768 | |
769 | if (mask > q->dma_alignment) |
770 | q->dma_alignment = mask; |
771 | } |
772 | EXPORT_SYMBOL(blk_queue_update_dma_alignment); |
773 | |
774 | /** |
775 | * blk_queue_flush - configure queue's cache flush capability |
776 | * @q: the request queue for the device |
777 | * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA |
778 | * |
779 | * Tell block layer cache flush capability of @q. If it supports |
780 | * flushing, REQ_FLUSH should be set. If it supports bypassing |
781 | * write cache for individual writes, REQ_FUA should be set. |
782 | */ |
783 | void blk_queue_flush(struct request_queue *q, unsigned int flush) |
784 | { |
785 | WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA)); |
786 | |
787 | if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA))) |
788 | flush &= ~REQ_FUA; |
789 | |
790 | q->flush_flags = flush & (REQ_FLUSH | REQ_FUA); |
791 | } |
792 | EXPORT_SYMBOL_GPL(blk_queue_flush); |
793 | |
794 | void blk_queue_flush_queueable(struct request_queue *q, bool queueable) |
795 | { |
796 | q->flush_not_queueable = !queueable; |
797 | } |
798 | EXPORT_SYMBOL_GPL(blk_queue_flush_queueable); |
799 | |
800 | static int __init blk_settings_init(void) |
801 | { |
802 | blk_max_low_pfn = max_low_pfn - 1; |
803 | blk_max_pfn = max_pfn - 1; |
804 | return 0; |
805 | } |
806 | subsys_initcall(blk_settings_init); |
807 |
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